1. Both the zoosporangia and the paraphyses originate from the superficial cells of the sporophylls.
2. The first and the second nuclear divisions in the zoosporangium are meiosis, and then three successive mitoses take place to form 32 free nuclei. Consequently 32 haploid zoospores are produced in a zoosporangium.
3. The haploid number of chromosomes in Costaria costata is about 30.
4. The centrosomes are visible at both poles of the spindle.